This invention relates to a scroll compressor utilizing linear motors to provide orbital movement of the orbiting scroll.
Scroll compressors are becoming widely utilized in refrigerant compression applications. Typically, a scroll compressor assembly includes a housing supporting a non-orbiting scroll. The non-orbiting scroll comprises a generally spiral wrap extending from a base. An orbiting scroll comprising a generally spiral wrap extending from a base is also supported by the housing. The generally spiral wraps of the scrolls intermesh to define a plurality of compression chambers. An electric motor drives the orbiting scroll in an orbit relative to the non-orbiting scroll and as the wraps orbit relative to each other, a refrigerant to be compressed is entrapped and moved toward a discharge port. The refrigerant is then discharged into a discharge pressure chamber.
Typically, the electric motor to drive the orbiting scroll extends linearly along a common axis. This configuration results in an extended overall scroll compressor axial length due to the axial length of a typical electric motor. A smaller scroll compressor would broaden the range of possible applications. For these reasons, it is desirable to design a scroll compressor with a reduced axial length.
A known scroll compressor configuration that reduces the overall axial length of a scroll compressor includes mounting of the electric motor radially outwardly of the interfitting scrolls. A scroll compressor of this configuration comprises an electric motor that is ring-shaped and mounted around the scrolls. The result is a scroll compressor assembly having a compact, relatively short axial length compared to a traditionally configured scroll compressor. However, a scroll compressor with such a co-axial configuration requires a custom manufactured electric motor instead of a low cost commercially available electric motor. Further, the integration of an electric motor and interfitting scrolls complicates assembly that in turn increases the overall cost of the scroll compressor.
For the above reasons it is desirable to provide a scroll compressor having a reduced or compact axial length that may be produced at a low cost.
A disclosed scroll compressor assembly includes a first linear drive for driving at least one scrolls along a first linear axis and a second linear drive for driving at least one scroll in a second linear axis. Preferably the second axis is transverse to the first linear axis. The linear drive moves a first and second scroll in an orbit relative to each other.
The subject invention also provides a method of operating a scroll compressor assembly having a first scroll interfit with a second scroll, and a first and second linear drive, attached to drive at least one of the scrolls. The method is comprised of the steps of oscillating at a predetermined frequency one of the first and second scrolls with the first linear drive along a first linear axis and oscillating at a predetermined frequency one of the first and second scrolls with the second linear drive along a second linear axis. The method further includes the step of controlling the frequency of oscillation of the first linear drive relative to the frequency of oscillation of the second linear drive to provide relative orbital movement between the first and second scrolls.
The two linear drives are inexpensive and fit within a small axial envelope. Accordingly, an axially compact scroll compressor is provided by the subject invention, allowing more space for specific applications and the broadening of potential applications. Further, the subject invention utilizes low cost commercially available linear drives simplifying assembly.
Further, with the present invention, capacity modulation can be easily achieved by controlling the drive motors. Capacity modulation is essentially changing the volume of refrigerant which is compressed. Three ways are disclosed to achieve such capacity modulation. First, the frequency of the X and Y drives can be varied together to achieved a change in the speed of the orbiting scroll, and hence the capacity. Secondly, the frequency of the X and Y drives can be varied out of synchronization with each other. This will result in wrap separation for a portion, or all of the orbit, and thus reduce capacity. Finally, the displacements of the X and Y drives can be varied to result in wrap separation, and thus a reduction in capacity. Other ways of changing the capacity can also be utilized.